METALLICA's James Hetfield and Kirk Hammett guest on In The Studio this week, talking about the 20th anniversary of their landmark self-titled album, more commonly known at the Black Album.

"On the 20th anniversary of Metallica (affectionately known as The Black Album in the same way THE BEATLES had been dubbed The White Album), we show in this week’s classic rock interview with Metallica’s lead singer/songwriter James Hetfield and lead guitarist Kirk Hammett how the band sits atop the family tree of hard rock/heavy metal evolution which you can trace back twenty years to DEEP PURPLE In Rock and the first BLACK SABBATH album. Like AC/DC’s Back In Black a decade before it, Metallica’s Black Album is the hard rock collection for people who thought they didn’t like hard rock! At more than 22 million copies sold, and with critics at Rolling Stone magazine ranking it #252 on their Top 500 Albums of All Time, you would assume that Metallica coasted unimpeded to this pinnacle , but quite the opposite is true."

Listen to the episode at this location.

Musicradar.com caught up with producer Bob Rock who talks about Metallica's Black Album.

“It wasn’t a fun, easy record to make,” says producer Bob Rock, speaking of Metallica’s self-titled fifth studio LP, popularly known as the Black Album. “Sure, we had some laughs, but things were difficult. I told the guys when we were done that I’d never work with them again. They felt the same way about me.”

When Rock began sessions with Metallica in the fall of 1990, the band (guitarist-singer James Hetfield, drummer Lars Ulrich, guitarist Kirk Hammett and their then-bassist Jason Newsted) had already hit platinum with 1988’s …And Justice For All, which catapulted them from cult stars to arena headliners.

“They had broken through to one level, but they still weren’t on mainstream radio,” says Rock. “When they came to me, they were ready to make that leap to the big, big leagues. A lot of people think that I changed the band. I didn’t. In their heads, they were already changed when I met them.”

Not that Rock didn’t help the group up their game any: Sonically, he gave them a rich, low-end punch that had been lacking in their previous recordings. Part of the process involved addressing Ulrich's drumming. “I noticed that Lars played to James’ guitar,” says Rock, “much like the way that Keith Moon played to Pete Townshend. That’s fine for some bands, but not every one.

“Lars wanted Metallica to groove more. AC/DC’s Back In Black was a big reference point as a rock record that grooved. I told him that in order to get that feel, he had to be the focal point musically. So on certain songs, the band played to Lars. They followed him. It made a real difference.”

Read the entire interview here.